JP2001084935A - Electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of visual field movement due to thermal expansion by detecting temperature around a visual field moving device and of a lens coil and controlling temperature and amount of cooling water. SOLUTION: A circulating device 16 cools in an objective lens part for reducing visual field movement caused by the thermal expansion of a mechanism system accompanied by temperature rise. Rapid control for temperature is, however, difficult because of control accuracy of a temperature sensor 20 and a water temperature control heater (2) 19 provided in a cooling water tank 15, the capacity of the water tank 15, and the like. The terminal voltage of an objective lens 2 is accordingly used as a temperature detecting signal 5, and a temperature control circuit 6 controls opening of a valve 12 for controlling the amount of the cooling water. Otherwise, a temperature control tank 21 is newly provided, and the amount of water and the temperature of the cooling water are controlled, corresponding to temperature change by providing a heater (1) 14 for controlling the water temperature in the water tank 21. The visual field movement due to the thermal expansion generated by fine thermal change can be thereby restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling water circulation mechanism for an electron microscope or the like, which is provided with a temperature sensor for the purpose of reducing the movement of an observation field of view and for controlling the temperature or flow rate of cooling water in a cooling water circulation device. To correct the amount of movement of the observation visual field.

[0002]

2. Description of the Related Art Conventionally, as in the case of a TEM, high-magnification observation and photographing have been supported by strictly setting conditions such as restrictions on the room temperature of installation and changes in the temperature of cooling water. At high magnifications, the movement of the visual field has been a problem until the temperature equilibrium after the apparatus is started. Specifically, sample moving mechanisms such as electron microscopes have problems such as the observation field of view moving for high-magnification observation, and the field of view moving when capturing an observation image, making it impossible to record images in a stable field of view. Will happen.

[0003] As means for avoiding such a problem, an air conditioner is attached to control the temperature at room temperature, or a heating portion such as a lens coil is cooled with water to reduce the movement of the observation field due to a temperature change. I'm doing the trick.

[0004] However, there is still a problem that the observation field movement affects the image recording due to the increase in the observation magnification, the temperature change around the mirror body, and the temperature equilibrium immediately after the power is turned on until the temperature equilibrium.

[0005]

In the conventional method, when a temperature change occurs around the lens coil and the mirror body,
Until the temperature of the mechanical system is balanced, the visual field shifts, and high-magnification observation and photographing cannot be performed.

An object of the present invention is to solve the above-mentioned problems by detecting the temperature around the visual field moving device, detecting the temperature of the lens coil, and controlling the cooling water temperature or the amount of cooling water to generate a mechanism in accordance with the temperature change. An object of the present invention is to provide a function of reducing the occurrence of visual field movement due to thermal expansion of the system.

[0007]

In order to attain the above object, according to the present invention, movement of a visual field due to thermal expansion caused by a temperature change is controlled by controlling a cooling water temperature or a cooling water amount flowing through a lens coil. Another object of the present invention is to provide a function of reducing a moving amount of a visual field.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A visual field movement correction of an electron microscope or the like as an example of an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a configuration diagram for the purpose of reducing the change in the field of view caused by a change in the ambient temperature and a change in the temperature of the lens coil in a field of view moving mechanism such as an electron microscope.

The sample 8 loaded in the sample moving device is configured so that an arbitrary visual field can be selected by a visual field moving mechanism. The selected field of view is sample 8, electron beam 10 scanning over
Is determined from the scanning area of. Every time the scanning area is reduced, it is enlarged to a high magnification.

The objective lens 2 comprises an objective lens control circuit 3 which can focus on the height of the sample 8 to be observed and the speed of the electron beam 10.

The objective lens section is provided with an objective lens water cooling pipe 4 for the purpose of reducing the movement of the visual field due to the thermal expansion of the mechanical system accompanying the temperature rise, and cooling with tap water or cooling with the circulation device 16 has conventionally been performed. Have been done.

The circulating device 16 is provided with a cooling water tank 15 in which a temperature sensor 20 and a heater (2) 19 for controlling the water temperature are incorporated, and the temperature is controlled by a cooling temperature control 18. It is difficult to control the water temperature without a temperature change due to the problem of accuracy and the capacity of the cooling water tank 15, and a change in the water temperature in a short time becomes a temperature change around the visual field moving mechanism, thereby causing a problem of moving the visual field.

Further, since the heat capacity of the objective lens and peripheral structures is large, the field of view moves until the temperature of the lens coil is equilibrated after the power is turned on, and the current of the objective lens is also increased by focusing. This causes the problem of drift.

In the present proposal, as one means for avoiding these problems, the terminal voltage of the objective lens 2 is used as the temperature detection signal 5 and the temperature control circuit 6 supplies a valve 1 for adjusting the cooling water amount.
2. Control the amount of water by. Alternatively, a temperature control water tank 21 is newly provided and a heater (1) 14 for controlling the water temperature in the water tank is provided.
By controlling the amount of water corresponding to the temperature change and controlling the cooling water temperature, it becomes possible to limit the movement of the visual field due to the thermal expansion generated by the minute heat change.

As described above, according to the present embodiment, it is possible to reduce the movement of the observation visual field and the visual field at the time of photographing an image, which are generated due to the temperature change of the periphery of the visual field moving mechanism and the lens coil.

[0017]

According to the present invention, in a mechanism used for a visual field moving mechanism such as an electron microscope, the visual field does not move due to thermal expansion caused by a temperature change, and the effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

1… Electronic optical system, 2… Objective lens, 3… Objective lens control circuit, 4… Objective water cooling pipe, 5… Temperature detection signal, 6…
Temperature control circuit, 7: Valve control signal, 8: Sample, 9: Drift, 10: Electron beam, 11: Cooling water supply, 12: Valve, 13 ...
Heater signal, 14 ... heater (1), 15 ... cooling water tank, 16 ... circulation device, 17 ... cooling water drainage, 18 ... cooling temperature control, 19 ... heater
(2), 20: temperature sensor, 21: temperature control water tank.

Claims (1)

[Claims] 1. An electron microscope having an electron source, a magnetic field lens for converging an electron beam emitted from the electron source, means for cooling the magnetic field lens, and a temperature for detecting a temperature of the magnetic field lens. An electron microscope, comprising: a detecting unit; and a unit configured to change a cooling efficiency of the cooling unit according to a temperature detected by the temperature detecting unit.